OK, Mariss over on CNCZone (of Gecko fame) has posted some thoughts which concur with my views on this... these boards are really only good for 1.8A and 30v maximum, IF you have a decent smoothing capacitor on the power supply (he recommends at least 1000uF and I'd suggest 2,200uF as a minimum - for more info read the thread here) If you are testing on a single axis and a switched mode PSU with no additional capacitor then beware as there is nowhere for the back-EMF energy to go.